Navigation system and navigation method

ABSTRACT

A navigation system and method having a function of alerting the driver to potential wrong way driving comprises means  102  for determining a position of a vehicle  300 , means  107  for calculating a driving route of the vehicle  300 , means  108  for determining a driving manoeuvre in accordance with the predetermined driving route  305 , means  104, 105, 110, 111  for outputting indications relating to the determined driving manoeuvre to a driver of the vehicle  300 , and means  109  for alerting the driver to potential wrong way driving including means  201  for detecting a potential wrong way driving situation and means  202, 104, 105, 110, 111  for outputting an indication relating to the potential wrong way driving situation to the driver.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/018,484, filed Dec. 17, 2004, titled NAVIGATION SYSTEM AND NAVIGATIONMETHOD, which claims priority to European Application Serial No. 03 029495.3, filed Dec. 19, 2003, titled NAVIGATION SYSTEM AND NAVIGATIONMETHOD, of which both applications are incorporated by reference in thisapplication in their entirety.

TECHNICAL FIELD

The invention relates to a navigation system and method approaches andmore particularly to navigation system and method approaches forpredetermining a driving route.

BACKGROUND

Navigation systems have become known in the art as computer-basedsystems that are mounted in a vehicle for calculating a driving route toa final destination input by the driver and outputting drivingindications for guiding the driver to the desired destination. Thedriving indications include announcements and instructions relating toforthcoming driving maneuvers, which have to be performed by the driverin order to follow the calculated driving route. The driving maneuversare determined by the navigation system based upon the calculateddriving route (i.e. crossings, junctions and the like) and output to thedriver, typically by an audio-response unit for voice output of thenavigation system.

More specifically, once a driving route to a final destination has beencalculated, the navigation system determines the driving maneuvers thathave to be performed by the driver at different points (locations) alongthe route while following the calculated driving route from the startingpoint to the final destination.

Subsequently, when the vehicle, which is traveling along the calculateddriving route, approaches the point of the route where a drivingmaneuver should be performed, different driving indications relating tothe forthcoming driving maneuver are output sequentially to the driverbased upon the distance to the respective point of the route.

As to the content of such driving indications, they typically comprisedifferent announcements of the forthcoming maneuver. For example, atfirst, a general announcement such as “turn off to the right comingsoon” at a rather long distance of 400-700 m may be output, followed byan advance announcement of the imminent maneuver including the distanceto the maneuver, such as “turn off to the right after 100 meters”, and,finally, in the immediate vicinity of the point of the maneuver, theinstruction to perform the driving maneuver such as “now turn off to theright”.

However, these different announcements output sequentially by thenavigation system may be confusing for the driver, in particular ifshe/he is not familiar with the use of a navigation system. Furthermore,it happens that the indications given by speech output via the audioresponse unit are missed or misinterpreted by the driver. As a result,it occurs that the driver does not comply with the instructions outputby the navigation system, what—in the worst case—may lead to asignificant deviation between the position of the vehicle and thecalculated route which should be followed by the driver, i.e., towrong-way driving.

In such a case, if the vehicle leaves the calculated driving route andwrong-way driving, i.e., a predetermined significant positionaldeviation between the set position of the vehicle according to thepredetermined driving route and the actual position of the vehicle, isdetermined by the navigation system by comparison of the actual positionof the vehicle and the calculated driving route, a modified drivingroute is calculated by the navigation system. As an example, EP 0 833291 B1 describes details relating to a method for “re-searching” thedriving route when the vehicle is out of the calculated route. Such amethod may include a search for an entire new route to the finaldestination from the current position of the vehicle, or, alternatively,the calculation of an additional route for returning to the originaldriving route calculated previously.

In both cases, the driver is provided with additional drivingindications as to the additional maneuvers that have to be performedaccording to the newly calculated modified driving route. Nevertheless,in any case a modified driving route means a detour as compared to theoriginal route what, of course, should be avoided.

SUMMARY OF THE INVENTION

An object of the invention is to overcome the above-mentioned problemsand to provide a navigation system and a navigation method capable toprovide improved driving indications which make it easier for the driverto follow the calculated route and which avoid that the driver ignoresthe driving indications.

The navigation system may comprise means for determining a driving routeof the vehicle, means for determining a position of a vehicle, means fordetermining a driving manoeuvre in accordance with the determined route,means for outputting indications relating to the determined drivingmanoeuvre to a driver of the vehicle, and means for alerting the driverto potential wrong-way driving including means for detecting a potentialwrong-way driving situation and means for outputting an indicationrelating to the potential wrong-way driving situation to the driver.

The invention also provides a navigation method for guiding a driver ofa vehicle comprising the steps of determining a driving route ofvehicle, determining a position of a vehicle, determining a drivingmanoeuvre in accordance with the determined driving route, outputtingindications relating to the determined driving manoeuvre to the driver,and alerting the driver to potential wrong-way driving by the steps ofdetecting a potential wrong-way driving situation and outputting anindication as to the potential wrong-way driving situation to thedriver, if a potential wrong-way driving has been detected.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the navigation system and thenavigation method become apparent from the following description ofpreferred embodiments with reference to the accompanying drawings inwhich

FIG. 1 is a schematic functional block diagram an implementation of anavigation system for altering the driver to potential wrong waydriving;

FIG. 2 is a schematic functional block diagram of the alert unit of thenavigation system shown in FIG. 1;

FIG. 3 is a schematic illustration of a situation of potential wrong-waydriving, and

FIG. 4 shows a flow chart of an embodiment of a navigation methodaccording to the invention for alerting the driver to potentialwrong-way driving in the situation illustrated in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

In one approach, a potential wrong-way driving of the driver is detectedby the navigation system and a respective indication is output to thedriver as an alert message. “Potential” wrong-way driving in the senseof the invention has to be understood as a situation occurring prior tothe above mentioned calculation of a modified driving route, i.e., asituation where the driver is still staying on the predetermined drivingroute. Accordingly, when the warning is output by the navigation system,the driver is still in the position to follow the originally determineddriving route and to comply with the instructions output by thenavigation system so that exclusively the driving maneuver(s) accordingto the originally calculated driving route have to be performed forreaching the final destination, i.e., without any additional turn off orturn back maneuvers which would be necessary according to a modified ora new driving route.

As a result of alerting the driver to potential wrong-way driving, theguidance of the driver by the navigation system according to thecalculated route is significantly improved, because, after the driverhas become aware of potential wrong-way driving, she/he may take stepsfor avoiding wrong-way driving in order to keep to the announcedmaneuvers according to the originally determined driving route, therebystaying on the calculated route.

Furthermore, since the driver is alerted early to potential wrong-waydriving, namely already at a point of the route which is stillcomparatively far distant from the point of the route where the maneuverhas to be performed, it is easier for the driver to initiatecountermeasures and to correct her/his driving behavior as compared tolater stages of the drive. This resides from the fact that the distanceto the imminent maneuver is still comparatively large so that the timeperiod available for initiating countermeasures and correcting thedriving behavior is comparatively longer.

Moreover, in many cases the traffic situation near the spot or thelocation where the maneuver has to be performed is more difficult forcomplying with the driving instructions output by the navigation systemas compared to earlier stages of drive. At the time of the announcementof a turning maneuver, for example, the driver might be standing in alane where a line of cars are standing from which it might be difficultto get into another lane for performing the turning maneuver. In such acase, due to an indication of the risk of wrong-way driving such as arepetition of the forthcoming driving maneuver output by the navigationsystem well before the point of the road where the turning maneuver hasto be performed, the driver's attention is heightened and focused on theforthcoming maneuver.

It is a further advantage to be capable to compensate for deficienciesof the database of map data used for navigation. For example, it occursthat the map data of the database does not reflect the precise point ofthe road where the driver should get into a certain lane in order to beprepared for a forthcoming turning maneuver, for example. In such a caseit may occur that at the time of the announcement of the maneuver, thedriver might already stand in a wrong lane from which it might be—notonly difficult—but prohibited by traffic regulations to get into thecorrect line for performing the turning maneuver, similarly to thesituation described above. Situations like that can be reliablyprevented by the navigation system and the method according to theinvention, whereby routing is significantly improved.

For determining the driving route, the navigation system according tothe invention may comprise means for calculating the driving route inaccordance with an information input by the driver, for example, a finaldestination. The information input by the driver may also relate to aroute section or a point which shall be included or excluded in theresulting driving route, for example, for defining a driving route fortransportation of dangerous media such as an ignitable liquid or gas, ora particular sightseeing route, city tour and the like. In particular inthe case of transportation of dangerous media it is extremely importantto ensure that the vehicle will not leave the predetermined drivingroute.

It goes without saying that the driving route may also be stored in thestorage device of the navigation system or on a server to which thenavigation system may have access by use of a communication device forselection of a driving route. Alternatively, the driving route may bedefined completely by user input without any calculation by thenavigation system. Preferably, the means for detecting a potentialwrong-way driving comprises means for detecting at least one value of atleast one parameter relating to an operation state of the vehicle, meansfor determining, in dependence on the predetermined driving route of thevehicle, at least one set value of parameters relating to an operationstate of the vehicle, means for comparing the detected values of theparameters and the determined set values of the parameters and means forjudging the result of the comparison for detecting a potential wrong-waydriving situation on the basis of the result of the comparison.

The set values of parameters, which is/are determined by means fordetermining at least one set value of said parameter(s) relating to theoperation state of the vehicle in dependence on the predetermineddriving route of the vehicle, may be a value indicating potentialwrong-way driving or a value indicating right-way driving.

In case where the set value defines right-way driving, “potential wrongway driving” has to be understood as a deviation of the actual values ofparameters relating to the operation state of the vehicle and thedetermined set values of the parameters or the respective rangesthereof. A predetermined amount of deviation may be defined, for example30%. Of course, the extent of deviation may strongly depend on the kindof the respective parameter and the respective traffic situation (speedlimit etc.) where the maneuver has to be performed and may vary from onesituation to another.

In case the set values defines) wrong-way driving, “potential wrong-waydriving” in the sense of the invention occurs if the actual value of aparameter relating to the operation state of the vehicle reaches thedetermined set value.

The definition of a set value which indicates potential wrong-waydriving or a value which indicates right-way driving aims infacilitating the processing of the large amount of data what is requiredfor detection of potential wrong-way driving.

Preferably, the set values of the parameters are only determined in thevicinity (i.e., within a predetermined distance) of a location of theroute where there is a possibility to leave the route by taking a wrongroad which does not belong to the predetermined driving route. For thispurpose, the means for alerting the driver to potential wrong-waydriving contains means for determining a location of the route where itis possible to leave the route, such as junctions, crossings and thelike, i.e., spots where wrong-way driving may occur. Thereby, checkingfor potential wrong-way driving can be restricted to route sectionswhere there is an actual risk for wrong-way driving, so that the amountof data processing necessary for potential-wrong-way driving can besignificantly reduced.

A parameter relating to an operation state of the vehicle in the senseof the invention may be a position of a vehicle, a time period, anadvancing direction of a vehicle, a position of a driving directionindicator control, an acceleration or a deceleration of a vehicle, avehicle speed, a rotational speed of a vehicle and the like. Theposition of the vehicle may be a relative position such as a distance toa predetermined location of the route or an absolute position, i.e., ageographical position.

Actual values of the parameters relating to an operation state of thevehicle are detected by suitable sensors known in the art (such asspeed, direction, temperature, turning, GPS location, tire pressure,etc. . . . ) that are connected to the navigation unit. The navigationunit typically will have a microprocessor, digital signal processor, ordigital controller. The sensors may continuously detect the currentvalues of the parameters relating to an operation state of the vehicle.For example, for determining an advancing direction of the vehicle agyroscope or a steering wheel sensor may be applied and the position ofthe vehicle may be determined by a GPS-system, GSSN-system or the like.A relative position of the vehicle, such as a distance to apredetermined location of the route may be determined based on theabsolute (geographical) position of the vehicle and map data stored in astorage device of the navigation system.

It has to be noticed that a positional deviation between the actualposition of the vehicle and the set position of the vehicle according tothe predetermined driving route does not necessarily indicate wrong-waydriving but, in dependence on the amount of deviation, may still fallunder the coverage of “potential” wrong-way driving. For example, thepositional deviation that occurs if a driver gets into the left lane,for example, near to a point of the road where the driver should turnoff to the right side may be detected as potential wrong-way driving.Preferably, staying on the predetermined driving route in the sense ofthe present invention may be defined as staying on the road (street) ofthe respective section of the originally predetermined driving route,including all driving lanes of the respective driving directions.

It should be understood that the respective parameters of the actualvalues and the parameters of the set values correspond to each other.The set values of the parameters may be time dependent, e.g. maintaininga vehicle speed (parameter) of lower than 50 km/h (value) for more than30 seconds.

The set values of the parameters relating to the operation state may bederived from a combination of two or more of the above-mentionedparameters. Without listing all possible combinations, in dependence onthe respective traffic situation, any of them may be utilized. Amongthat large variety, in particular a combination of the position of thevehicle and one or more parameters from the group vehicle speed,direction indicator control, advancing direction of the vehicle, and thetime period during which these parameter are within at least onepredetermined range of values is preferable for detection of potentialwrong-way driving. More preferably, the set value of the parameterrelating to an operation state of the vehicle may be a relative positionof the vehicle which is defined by a distance to a location of the roadwhere the driving maneuver has to be performed and, additionally, by adistance of the position of the vehicle to the predetermined drivingroute. Such a definition of set values (here: two distances) of therespective parameter (here: relative position) may be helpful toincrease the accuracy of detection of potential wrong-way driving. Theset values of the two distances may also be set in dependence on eachother. For example, the distance to the predetermined driving routerequired for the detection of potential wrong-way driving may decreasewith the decrease of the distance to the point of the road where thenext turning off maneuver has to be performed.

Of course, the means for determining at least one set value of theparameters relating to the operation state of the vehicle and the meansfor detecting at least one actual value of these parameters may beadapted to these preferred configurations by comparing the respectivedetermined parameters to the set values of the parameters, such as theabove two distances and the actual values thereof during the operationof the moving vehicle, respectively.

The set values of the parameters are determined based upon thepredetermined driving route. Since for following the predetermineddriving route different operation states of the vehicle in terms ofparameter values of velocity, advancing direction and the like arerequired at different locations of the route, the at least one set valueof parameter(s) is determined in dependence on the circumstances atindividual locations of the respective driving route or driving routesection. More in detail, the set values may be determined in dependenceon the kind of the driving manoeuvre, the traffic regulations along therespective route section and/or the course of the road along the drivingroute section. As a simple example for illustration, a turning offmanoeuvre at a turning off angle of more than 90° requires a lowervehicle speed than a turning off angle of 30°.

By using, for example, the position of the direction indicator controlas a parameter relating to the operation state of the vehicle fordetermining a potential wrong-way driving according to the invention,the occurrence of a positional deviation between the actual position ofthe vehicle and the predetermined driving route is not, necessarilyrequired for detecting potential wrong-way driving. A relating examplemay be a predetermined route going straight ahead, on the one hand, andsetting of the direction indicator control to a certain position, e.g.,for turning left, by the driver and maintaining it in this position forlonger than a predetermined time period without changing the drivingdirection. In such a case, the intention of the driver to turn off tothe left is detected by the navigation system and a potential wrong-waydriving is concluded, i.e. detected. A further example of thedetermination of a potential wrong-way driving may be an excessivevehicle speed determined at a position near the location of a turningoff maneuver according to the predetermined route.

In other words, the navigation system according to the invention iscapable to alert the driver to potential wrong-way driving while thevehicle is still staying on the predetermined driving route. In oneapproach, the means for outputting an indication relating to potentialwrong-way driving to the driver comprises means for determination thecontent of indication output to the driver.

The means for determining the content of indication output to the drivermay comprise means for determining output information relating to thecorrect driving route, i.e. the originally predetermined driving route.Thereby, the driver's attention is drawn to the risk of wrong-waydriving, so that she/he can easily conclude what has to be done forstaying on the correct route. For more complicated situations, where itis rather difficult for the driver to infer what to do, the means fordetermination the content of indication output to the driver maycomprise means for determining driving recommendations for avoidingwrong-way driving. That is, in dependence on the situation of potentialwrong-way driving, instructions may be output to the driver on how tostay on the predetermined driving route. Said driving recommendation tobe output to the driver as determined by means for determining drivingrecommendations may include an indication relating to the parameter usedfor determining the potential wrong-way driving. For example, such anindication may relate to the vehicle speed or to the position of thedriving direction indicator. The indication may also include informationrelating to the set value of the respective parameter. For example, thedriver may be informed that the vehicle speed is too high for performingthe following turn-off maneuver in accordance with the predetermineddriving route. In other words, the indication to be output to the drivermay include information relating to the deviation between the actuallydetected parameter relating to the operation state of the vehicle andthe set value determined in accordance with the calculated drivingroute.

By outputting such a recommendation for avoiding wrong-way driving, thedriver is assisted in following the predetermined driving route withoutpaying attention to, for example, the display of the navigation system.Accordingly, the driver can rely completely on the output drivingrecommendations for following the route. The output means for outputtingdriving indications to the driver may comprise an audio-response unit incombination with loudspeakers and/or a display of the navigation system,such as a LCD display, Plasma Display, CRT display.

In FIG. 1, a navigation system 100 is shown. The navigation system inFIG. 1 has a navigation unit 101, a position determination unit 102including a GPS-unit 121 and a unit 122 for determining a relativeposition of a vehicle, an operation panel 103, a display 104, a set ofspeakers 105 and a storage device 106. An audio-response unit (ARU) 110including a text-to-speech (TTS) synthesizer 111 and a speechrecognition unit 112 for voice command purposes are connected to thenavigation unit 101. The input/output equipment of the navigation system100 according to the present embodiment is constituted of the operationpanel 103, the display 104, the audio-response unit (ARU) 110 includingthe text-to-speech (TTS) synthesizer 111 and the speech recognition unit112. However, the configuration of the input/output equipment is notlimited thereto and any kind of human machine interface known in the artfor transferring data between user and system may be provided independence on the demands of the individual user. For example, thedisplay 104 may be constituted of a touch screen and the operation panel103 may comprise a joystick and/or a microphone not shown in FIG. 1. Thenavigation unit 101 comprises a driving route-calculating unit 107, adriving maneuver determination unit 108, and an alert unit 109 that isdescribed in more detail below with reference to FIG. 2.

The storage device 106 is a mass storage medium for storing map dataconstituted of a CD-ROM and a CD-ROM drive, for example, and isconnected to the navigation unit 101 and the position determination unit102. The navigation system 100 according to the invention furthercomprises as a plurality of sensors including a steering wheel sensor113, a rotational speed counter 115, wheel sensors 116, ABS sensors 117,a gyroscope 118, and a sensor 119 for determining the position of thedriving direction indicator control as well as a timer 120 which areconnected to the navigation unit 101. A unit 114 for providing atachometer signal is also connected to the navigation unit 101.

The alert unit 109 of the navigation unit 101 of the navigation system100 shown in FIG. 1 is illustrated in more detail in FIG. 2. The alertunit 109 comprises a potential wrong-way driving detection unit 201, anindication content determination unit 202 and a unit 208 for determininga location of the route where it is possible to leave the route. Theunit 208, determines locations of the route where it is possible toleave the route on the basis of the calculated driving route asdetermined by the driving route calculation unit 107 and the map dataprovided by the storage device 106.

The potential wrong-way driving detection unit 201 includes a set valuedetermination unit 203 for the determination of set value(s) of aparameter(s) relating to the operation state of the vehicle. The setvalue determination unit 203 comprises a plurality of subunits fordetermining at least one set value of at least one parameter or acombination thereof from the group: geographical position of a vehicle(unit 210), relative position of a vehicle (unit 211), advancingdirection of a vehicle (unit 212), position of a driving directionindicator control (unit 213), acceleration/deceleration of a vehicle(unit 214), vehicle speed (unit 215), rotational speed of a vehicle(unit 216) and a time period during which at least one value of saidparameter(s) is within a predetermined value range (unit 217), which—forthe sake of simplicity—are illustrated in FIG. 2 as an unitary componentwith reference numerals 210-217.

The potential wrong-way driving detection unit 201 may have a comparator204 for comparing the set value(s) determined by the set valuedetermination unit 203 and the actual values determined or detected bythe position determination unit 102 including units 121 and 122 and/orthe sensors 113-120 including unit 114. A judging unit 205, such as aprogram executed by a controller, microprocessor, or digital signalprocessor is provided for judging the result of the comparison performedby the comparator 204.

The indication content determination unit 202 may have a unit 206 fordetermining output information relating to the correct driving route anda unit 207 for determining driving recommendations for staying on thecorrect driving route (i.e., the originally calculated driving route) independence on the detected potential wrong-way driving situation.

A situation of potential wrong-way driving is illustrated schematicallyin FIG. 3. A vehicle 300 is moving along a three-lane road 301comprising lanes 302-304. More specifically, the vehicle 300 is movingalong traffic lane 302 at point “A” of road 301 when the navigationsystem 100 of the vehicle 300 outputs an advance announcement of amaneuver “right-hand turn after 400 meters” in accordance with thecalculated driving route 305 indicated as a dotted line in FIG. 3. Thedriver who heard the advance announcement notices the crossing 306 lyingahead and misinterprets the advance announcement output by thenavigation system as to be related to crossing 306 instead of crossing307. As a result, the driver operates the lever of the driving indicatorcontrol for moving to the right, reduces the vehicle speed, and switchesfrom lane 302 to lane 304 at point “C” of the road 301.

Accordingly, since in the present situation the driver misunderstood theadvance announcement output by the navigation system at point “C” ofroad 301, there is a risk that the driver turns off to the right side atcrossing 306 instead of crossing 307 according to the calculated drivingroute 305. In other words, at point “C” of road 301 a situation ofpotential wrong-way driving in the sense of the invention occurs.

Such a situation of potential wrong-way driving can be recognized andwrong-way driving can be avoided by the use of a navigation system, forexample.

In the following an implementation of a navigation method according tothe invention for guiding a driver of vehicle 300, if a potentialwrong-way driving situation as shown in FIG. 3 happens, is describedwith reference to FIG. 4.

In step 400, after starting the engine of the vehicle, the position ofthe vehicle is determined by the position determination unit 102 of thenavigation system 100. In the following the determination of thegeographical position is continued periodically during the drive by theposition determination unit 102. In step 401, after an input of adesired destination by the driver via the operation panel 103, a drivingroute to the final destination is calculated by the driving routecalculation unit 107. The resulting driving route from the startingpoint to the final destination as input by the driver includes a routesection constituted of sections of roads 301 and 308 shown in FIG. 3.While in the present implementation the driving route has beenpredetermined by calculation in accordance with an input information(final destination), the driving route may also be predetermined byselection and download from an external server via the internet, forexample.

For following the calculated route, a plurality of driving maneuvers isdetermined in step 402 by the driving maneuver determination unit 108.Among these maneuvers, there is a right-hand turn off maneuver atcrossing 307 in order to reach road 308 coming from road 301 as shown inFIG. 3.

During the drive the distance to crossing 307 where the turning offmaneuver to the right has to be performed is continuously determined instep 403 by the unit 122 for determining a relative position of thevehicle by comparing the actual position of the vehicle 306 asdetermined by the GPS system 121 and the location of crossing 307 basedon map data of the storage device 106.

In step 404, when reaching a predetermined distance to the location ofthe maneuver such as 200 m to crossing 37, the advance announcement“turn off to the right after 200 meters” is output to the driver by theaudio response unit 110 via loudspeakers 105. Furthermore, in step 405 aset value of parameters relating the operation state of the vehicle isdetermined by the set value determination unit 203. In the present case,the set value of the parameters represents a value that indicatespotential wrong-way driving and is constituted of a combination of theparameters position of the vehicle, vehicle speed, position of thedriving direction indicator control and time. The specific values ofthese parameters are set as follows:

Condition A: a distance of the vehicle to crossing 306 of less than 300meters,

Condition B: a vehicle speed lower than 40 km/h for more than 5 seconds

Condition C: a downward position of the driving direction indicatorcontrol maintained for more than 5 seconds.

In the present embodiment, since the position of the vehicle 300 iscontinuously determined by the position determination unit 102 of thenavigation system 100, in the following merely the position of thedriving direction indicator control is determined by sensor 119 in step406. If the driving direction indicator control is set to a downwardposition indicating the willingness of the driver to perform a turn offmaneuver to the right, in step 407 the timer 120 is started and the timeperiod of the driving direction indicator control being set to thedownward position is monitored.

As mentioned above, the set value of parameters for defining a potentialwrong-way driving in the present embodiment is defined by thecombination of the conditions A+B+C. Accordingly, in step 408 the actualposition of the vehicle as determined in step 400 by the positiondetermination unit 102 of the navigation system 1 is compared with theset position according to condition A; in step 409 the speed of thevehicle obtained from the tachometer signal unit 114 is compared withthe set value as specified by condition B and in step 410 the positionof the driving direction indicator control as determined by sensor 119in step 406 is compared with the set value as specified by condition Cby means of the comparator 204.

If no potential wrong-way driving is detected in step 411 by the judgingunit 205, in step 412 an advance announcement as to the approachingcrossing 307 is output when the vehicle which is following thecalculated driving route reaches a predetermined distance to the pointof the route where the maneuver has to be performed, i.e., the crossing307, what is determined by the relative position detection unit 122. If,in step 411, a potential wrong-way driving is detected, in step 413 thecontent of indication relating to potential wrong-way driving isdetermined by the indication content determination unit 202. That is,according to the example of the present embodiment, the current distanceto the driving maneuver (here: 200 m) and the kind of driving maneuver(here: turn off to the right) are determined as the information to beoutput to the driver by the unit 206 for determining output informationrelating to the correct driving route. Furthermore, in step 414 adriving recommendation for avoiding wrong-way driving is determined bythe unit 207 for determining driving recommendations for staying on thecorrect driving route. In the exemplary situation of the presentembodiment, from the location of crossing 307, the position of thevehicle and the course of the road between the location of the crossing307 and the position of the vehicle 300 at point C of road 301, asillustrated in FIG. 3, based on the map data stored in the storagedevice 106, it is determined that going straight ahead is theappropriate driving behavior for reaching crossing 307 from the currentposition of the vehicle 300 at point C.

Accordingly, the following warning is output in step 415 to the driver:“Attention; possibly wrong-way driving; Keep going straight ahead; turnoff to the right after 200 m”.

Further embodiments relating to methods according to the invention aredescribed in the following. The embodiments 2 to 5 are based on theabove first embodiment described with reference to FIGS. 3 and 4 butcomprising the following modifications:

According to a second embodiment, instead of the detection of potentialwrong-way driving in dependence on the combination of set valuesaccording to the above conditions A+B+C, wrong-way driving may also bedetected by a combination of set values A+B or A+C.

According to a third implementation, instead of calculating a set valuebeing an indicative value of said parameter relating to an operatingstate of the vehicle for leaving route, a value of said parameterrelating to an operating state of the vehicle which indicates that thevehicle is staying on the route is calculated as a set value.Specifically, instead of condition “B” a speed range of Vset>40 km/h isdetermined as a set value (condition D) based on the speed limit of 70km/h on road 301. If the vehicle speed falls below 40 km/h, potentialwrong-way driving is concluded since the reduction of speed isinterpreted as an indication that the driver intends to turn off atcrossing 306.

As becomes apparent from the above implementation, the determination ofset values strongly depends on the traffic regulations at the respectiveroad sections or locations. For example, according to a fourthembodiment, if a traffic signal is installed at the crossing 306 theabove conditions “A” and “D” are not sufficient because it has to beexpected that the vehicle has to stop at the traffic light whataccording to the conditions A+D or A+C would lead to a detection ofwrong-way driving, erroneously. In order to distinguish between waitingat the traffic light and potential wrong-way driving, in such a case acombination of conditions A+B+C is necessarily required.

A further important factor for the determination of the set value is thedriving route and the circumstances at the point of the road where themanoeuvre has to be performed. For example, according to a fifthimplementation, potential wrong-way driving is to be detected in thearea of crossing 307 where the driver has to get on route 308 forfollowing the calculated driving route, as shown in FIG. 3.

Accordingly, the set values of parameters indicating potential wrong-waydriving may be defined as follows:

Condition E: a distance of the vehicle to crossing 307 of less than 150meters,

Condition F: a vehicle speed higher than 70 km/h

That is, if the vehicle exceeds a speed limit of 70 Km/h within acomparatively small distance of 150 meters to crossing 307 this isinterpreted as an indication that the driver will not turn off to theright at crossing 37 but intends to drive straight on along road 301what would lead to wrong way driving.

It goes without saying that the implementations 1-5 as described abovemay be combined in any manner suitable to put the invention intopractice, according to the knowledge of a person skilled in the art independence on the particular demands of the respective application.

1. A navigation method for guiding a driver of a vehicle comprising;predetermining a driving route of the vehicle; determining a position ofthe vehicle; determining a driving maneuver in accordance with thepredetermined driving route; alerting the driver to potential wrong waydriving by detection of a potential wrong way driving situation; andoutputting an indication relating to said potential wrong way drivingsituation to the driver, if a potential wrong way situation has beendetected.
 2. The navigation method according to claim 1, furtherincluding: detecting a potential wrong way driving situation when atleast one value of a at least one parameter relating to an operationstate of the vehicle; determining at least one value of at least oneparameter relating to an operation state of the vehicle based upon thepredetermined driving route; comparing the detected value and thedetermined values; and judging the result of comparison to detect apotential wrong way driving situation.
 3. The navigation method of claim2, where the determined value is based upon traffic provisions along thepredetermined driving route.
 4. The navigation method of claim 2, wherethe determined value based upon the determined driving maneuver.
 5. Thenavigation method of claim 2, further includes: determining a locationof the predetermined driving route where it is possible to leave thepredetermined driving route.
 6. Navigation method of claim 2, where thedetermining the at least one value further includes: determining the atleast one value within a predetermined distance to a point of thepredetermined driving route where the driving maneuver is to beperformed.
 7. The navigation method of claim 2, where the at least oneparameter(s) is selected from a group of parameter comprising: ageographical position of the vehicle, a relative position of the vehiclewith respect to at least one location of the predetermined drivingroute, an advancing direction of the vehicle, a position of a directionindicator control, a vehicle speed, a rotational speed of the vehicle,and a time period during which any parameters are within one or morepredetermined ranges of values.
 8. The navigation method of claim 7,where value of the respective parameter is selected based upon anothervalue of another parameter and a distance to a point in thepredetermined driving route where the determined driving maneuver is tobe performed.
 9. The navigation method of claim 2, further comprises:determining an output information related to said predetermined drivingroute which is to be output to the driver upon detection of thepotential wrong way driving situation.
 10. The navigation methodaccording to claim 2, further comprising: inputting information relatingto a desired driving route; and calculating the predetermined drivingroute in accordance with said input information.
 11. The navigationmethod according to claim 2, further comprising selecting a drivingroute from a plurality of driving routes stored on a storage medium ofan external server.